Automatic trunking apparatus for electrical circuits.



L. O. SURLES. AUTOMATIC TRUNKING APPARATUS FOR ELECTRICAL CIRCUITS.

APPLICATION FILED JUNE 30, 1906.

Patented Apr. 27, 1909.

3 SHEETS-SHEET l.

L. O. SURLES.

AUTOMATIC TRUNKING APPARATUS FOR ELECTRICAL CIRCUITS.

APPLICATION FILED JUNE so, 1906. 91 9,49 l Patented Apr. 27, 1909.

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L. 0. sURLEs. AUTOMATIC TBUNKING APPARATUS FOR ELECTRICAL CIRCUITS. Arrmonion FILED JUNE 30, mos.

Patented Apr; 27, 1909.

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LAWRENCE O. SURLES, OF ATLANTA, GEORGIA.

AUTOMATIC TRUNKING APPARATUS FOR ELECTRICAL CIRCUITS.

Specification of Letters Patent.

Patented April 27, 1909.

Application filed June 30, 1906. Serial No. 324,154.

To all whom it "may concern:

Be it known that I, Lnwnnncn O. SUnLns, a citizen of the United States, residing at Atlanta, in the county of Fulton and State of Georgia, have invented new and useful Improvements in Automatic Trunking A paratus for Electrical Circuits, of which t 1e following is a specification.

This invention relates to automatic trunking ap aratus for electriol circuits, being particn arly applicable to te ephone and telegraph circuits. i

The objects of the invention are to reduce the quantity of, and simplify, the apparatus required, thereby facilitating the operation and reducing the cost of construction and installation.

These objects may be accomplished by the use of the present invention in connection with electrical circuits in general and more particularly in connection with telegraph and telephone circuits and in the latter case whether the system is manual or automatic and common battery or otherwise.

The invention is illustrated in the accon1- panying drawings of which- Figure 1 is a diagram illustrating the application of the invention to a common battery manually operated system with trunks for connecting between exchanges, Fig. 2 illustrates the application of the invention to a Strowger automatic system, Fig. 3 is a side elevation of a selective device partly broken away, l ig. 4 is an end elevation of the same, and Figs. 5, 6, 7 and 8 are views of details .Of the selective device as will be hereinafter referred to.

prises a plurality of subscribers stations A, A, etc, signaling conductors B, B, etc, through which the-signaling or talking current is transmitted. A cord circuit by which it is intended to indicate any means and the apparatus appurtenant thereto at a central station or other point for connecting togethertwo subscribers lines so that their connected stations are placed in communica tion, selective devices I), 1), etc, for connecting the signaling conducors extending from the subscribers station with any one of a plurality of cord circiiits, it being understood that a cord circuitis associated with the selective device D and others in the same manner as the cord circuit is shown to be associated with the selective device D, and

selective conductors E, E, etc, corresponding to their respective stations for controlling the operation of the selective devices.

The manner of application of the invention to the connecting of trunks between exchanges, is shown only in Fig. 1, as the manner of its application to automatic exchanges, such as illustrated in Fig. 2, would be obvious, the necessary modifications being readily made by telephone engineers. Illustration of the application of the invention to trunks between exchanges has therefore been omitted from Fig. 2.

Each of the selective devices may comprise (Figs. 3 to 8 inclusive) a shaft 1 cont inuously driven by any suitable means, as a pulley 2, to which a belt may be applied. The shaft is rotatably mounted in suitable bearings in a frame 3. Carried by the frame are a plurality of sets of contacts 4, 5, 6, etc, corresponding to the number of subscribers stations. These contacts are arranged in arcs concentric about.the axis of the shaft 1. Thecontacts of each set are adapted to be engaged by sweepers or movable contacts 7, 8, 9 and 10, there being a sweeper for each of the stationary contacts of a set and the sets are adapted to be successively engaged as the sweepers move in circles about the axis of the shaft 1. The movable contacts or sweepers already referred to are in fixed electrical connection with collars 11, 12, 13 and 14 insulated from each other and from their support by means of an insulating spool 15 which is loose upon the shaft 1 but is adapted to be secured thereto by a clutching device which may consist of a toothed member 16 fixed upon the shaft and adapted to engage with toothed member 17 fixed to the spool 15. When the spool is clutched to the shaft it turns therewith carrying the sweepers 7 to 10 and connection with collars 11 to 14 is maintained during the revolution by means of fixed contacts 18, 19, 2 0 and 21 which bear upon the said collars and are supported upon the frame 3 in such manner as to be insulated therefrom and from each other. A convenient means of effecting this support is by clamping'the contacts 18 to 21 between insulating plates 22 and 23 which are drawn toward each other and secured to the support by means of bolts 24 (see Fig. 8).

Supported by the frame 3 is an electromagnet 25 having an armature 26 normally withdrawn from the magnet as by a spring 27. This armature is fixed to a vertical rod a groove-'30 in a hub 31 secured to the spool 15. Upon the attraction of the armature 25 by the magnet 25 the rod 28 will be turned upon its axis thereby shifting the forked end oi the member 29 along the shaft 1 and lthereby drawingthe spool with it, thus disengaging the clutch members 16 and l? and releasing the spool 15 from the shaft. The drawing of the spool 15 alongthe shaft, in addition to disengaging the clutch members, whereby the sweepers are brought to a stop, also serves to bring the sweepers 7 and 8 into engagement with their corresponding stationary contacts, these sweepers, when the connector is in its normal condition (that is,

, in the osition as shown in 31' .3 and revolving with the shalt) not being in position to engage with the stationary contacts, this engagement being only ellected when the spool has been drawn to the right and stopped in connecting position. in order that the spool may be stopped accurately in position anotched disk 32 isfixed to the spool and when the latter is drawn along the shalt to release it from connection therewith, as before described, the notched dish will ride upon a stop 33 fixed to the frame which by entering one of turning of the spool in either direction. it will be noted that the sweepers 7 to 10 and the stationary contacts 18 to 21 are provided with springs whereby the longitudinal movement oi the spool is permitted while the respective sweepers and contacts are in engagement without breaking the; contacts. The'magnet 26 also servesto control two pairs of contacts 34 and 35 which are mount ed upon the frame 3 and by reason of being formed of springniaterial or in other ways they tend to close. The individual contacts of these pairs are insulated from the frame and from each other. Upon the armature 26 is inounted an insulating projection 36 which, When the magnet is denergized, bears upon one of the pairs of conthc ts 34 thereby opening the same and through an insulating piece 37 interposed between a contact of the pair 34 against which the projection 36 bears, and one of the contacts of pair 35, the armature operates when denergized to open ooth pairs, of contacts 34 and 35. \"Fhen the magnet 25 is energized and its armature attracted the pairs of contacts 34 and 35 will be respectively closed. The pur ose of these pairs of contacts 34 and 35 wi be hereinaiter set forth.

Each of the subscribers stations *A, A, etc, comprises the usual transmitter 38 and a receiver which may be connected in a well known manner and is not here illustrated, the receiver hook 39, and contacts -20 adapted to be closed when the receiver is removed from the hook. One of the contacts 40 is the notches will prevent the cord circuit.

connected through contacts 41 with round ch42. The contacts 41 are controlled by a relay 43 in the signaling, that is, in the talking ircuit. From each station extends signaling wires 44 and 45 connected with stationary contacts 4, 4', i, 4 etc, of the selective devices D, D, etc. The selective conductors E corresponding to the station A are connected to stationary contacts 4, 4 of the selective device D, stationary contacts 4' M of the selective device D and so on to analogous stationary contacts of all the selective devices. signal conductors B andselective conductors ll corresponding to the station A are connected to the set or contacts 5 to 5' at the selective device D and to the set of contacts 5 to 5 at selective device l), and in simi, lar manner are connected to any number of other selective devices. In a similar manner each or" the stations is provided with a corresponding set of contacts in any desired number of connecting devices. each of the cord circuits C and the selective devices D, D", etc, is identical and the manner of making connections is the same for each selective device and cord circuit, a description of one of them will be sufi'icient. The cord circuit comprises the signaling conductors 47 and 48 connectedto the stationary contacts 18- and 19.0f the selective device: l) and is continued through the repeating coils 49 and 50 and conductors 51 and 52 to the plug 53 -by which connection can be made. with any dcsiredfsubscribers station by in sorting it in the proper jack as is well understood. Between the re eater coils 49 and 5G is connected a source of electricity such as a battery 54 adapted to sup ly the signalingcurrent, in this case the talking current, to connected stations.

Across the conductors 5i and 52 is connccted the well known listening key 55 to which is connected the operators a paratus. This apparatus and the manner 0' its connection and operation is so well understood that it is not shown and'needs no further description.- The device 56 for ringing up the called subscriber is also well known in the art and will not be further, described. Con nected with the sleeve of the plug 53 is a re} sistance-57 through whichthe circuit of a supervisory signal such asja lamp 58 may be completed when the contacts 59- are closed to the battery 54 by the energization of the relay 60 in the called subscriber side of the One side of the battery it will be noted is grounded at 61. A resistance 62 is shunted about the lamp 58 and contacts 59 to provide a path for current sistance 57 from the sleeve of jack 53 to the battery 54 when the contacts 59 are open. The utility of this will be more fully explained in describing the connection of trunks between exchanges.

It will be unthrough the re- In a similar inanner the ios derstood thatthe resistance 62 is so proportioncd with relation to that of the lamp that when the contacts 59 are closed sul'licient current will be shunted through the'larnp to light it. In the signaling conductor on the calling side of the cordcircuit is a relay 63 adapted when energized by the'signaling curbattery 54, the selective device D, a selective conductor 67, contacts 68, and signaling conductor 44, contacts 40, contacts 41 and ground at 42. The energizing of the magnet 66 as described operates to close the norymally opencontacts 69 thereby closing'a circuit through the battery 54, electromagnet and supervisory signal 65, the last two mentioned devices being connected in parallel. Upon the energizing of the magnet 25 the contacts 34 are closed thereby closing a circuit through the battery 54, selective device D, selective conductor 71 and relay 72.

be connected; with" another The energizing of the relay 72 opens the contacts 68 thereby opening thecircu-it of and denergizing the relay 66. It also closes the contacts 73 thereby connecting the conductor 74 with ground, the conductor 74 being connected with'the jacks corresponding to thestation A and providing a busy test in a well known manner. 1 1

' The apparatus concerned having been indicated, the operation "ofconnecting two subscribers may be outlined and circuits traced as follows: Let it. be assumed that a subscriber at" any station, as A, desires to ub'scribers station. The first operation is to remove the receiver from the receiver hook 39 which results in the closure of the contacts 40 and 46 as before described This places a ground on the signaling conductor 44., The shaft 1 being revolved continuously all of the spools carrying connecting sweepers which are not in use and therefore disconnected from the shaft or,-in other words, all the idle sweepers will be turl'ling with the shaft. The teeth of the clutches for securing the spools to the shaft 1,.' as hercinbcfore referred to, are

angularly displaced about the shaft so that.

no two sets of sweepers will come in contact with sets of stationary contacts corresponding to one subscribers station at the same time] The first set of sweepers of any of the selective devices D, 1), etc, to come in contact with'a set of stationary contacts corresponding to the station A, in the instance.

supposed, will'cll'oct the connection of sevf oral circuits and the bringing about of certain operations in the cord circuit connected to that selective device as will now be set forth in connection with the selective device D, the sweepers of which it will be assumed are the first to Contact wlth a set of stationary plug 53. also has the effect of permitting the closure scribcrs in the usual manner.

contacts corresponding to station A. The contacting of the sweepers 9 and 10 in clusive'with the stationary contacts 4 and 4 inclusive having been accomplished, circuit may be traced from the ground at 42 through contacts 41, contacts 40, signaling conductor 44, contact 68, stationary. con.- tact 4, sweeper 9, stationary contact 26, relay 66 and battery 54 to ground at 61. The relay 66 being thus energized the contacts 69 are closed, thus closing circuit through the supervisory lamp 65 and the electromagnet 25 in parallel through the battery 54. The magnet 25 being thus energized attracts its armature 26, ther' upon shifting the spool 15 along the shaft and disengaging the. clutch members 16 and 17 while looking the spool in position by means of the stop 33 and notched disk 32, and bring ing the sweepers 7 and -8 into engagement with their respective stationary contacts, all as previously described. The sweepers are thus stopped in connecting position and the signaling conductors 44 and 45 are connected through the stationary contacts 4 and 4, sweepers 7 and 8 and stationary contacts 1S and-19 to the signaling conductors .47 and 48 of the cord circuit and thence through signaling conductors 51 and and The attraction of the armature 26 of the contacts 34 thereby closing a circuit through the battery 54, stationary contact 21, sweeper" 10, stationary contact 4', selective cr-nductor 71 and -relay 72 to ground.- The relay being thus energized opens the contact at 68 and thereby removing the groundfrom the selective conductor 67, previously connected thereto through the signal conductor 44, prevents the formation of a circuit through the relay at any other station corresponding to the rclay 66, and thereby prevents a set of sweepers at any other selective device from stopping on the set of contacts corresponding to the stat ion A. The relay 66 having been denergized and the contact 69 open, the circuit through the supervisory signal and the eleciromagnet 25 is maintained through the con; acts 64 which are held closed by the relay 63 which is energized by the signaling current supplied to the station .A by .the battery 54. A further effect of the energizing of the relay 72 is the application f (be busy test to the jacks cf the stalicn A.

(lonneciirns having been made as dcscribed the lighting of the lamp 65 will indicate to the operator that a subscriber is connected to that cord ciicuitan'd desires connection. key'55 in the usual manner and ascertaining what subscriber is desired, the plug 53 is in- I sorted in an appropriate jack as when the circuit will be oomph-ted between the sub- Thc called He will then press the listcning connected stations.

- a setbf stationary contacts corresponding subscriber may then be rung up by operating the ringing device 56 in the well known manner. The called subscriber having been rung up, he removes his receiver from the hook thereby completing the signaling or talking circuit as is Well understood, the battery 54 serving as a common battery, that is su plying transmitter or signaling current to t e The signaling or talking circuit having been thus completedthe relay 60 will be energized thereby closing the contacts 59 and completing a circuit from the ground at 61 through the battery 54 and signal lamp 58 to ground at 81. The subscribers will then be in si naling communication and the lamps and 58 will be lighted. It will also be noted that the establishment of circuit through the battery 54 and the station A energizes the relay A3, thereby opening the contact 41 and removing the round from the signaling conductor 44. gonversation may now be carried on throu h the two connected subscribers and upon t e completion of the conversation the hangin up of the receiver hook at station A wil break the contacts at; thereby denel'gizing the relay 63 and opening the circuit through the battery of the lamp 65 and the electroinagne't 25. Thedeenergizing of the magnet 25 will permitits armature 26 to moveunder the influence of spring 27 thereby turning the rod 28 upon its axis and sliding the spool carrying the sweepers into engagement with the shaft as before described. The. retrac-' tion of the armature 26 also operates to open the contact 34 thereby denergizing the relay 72 so that the contacts'68 and 73 may assume their normal 'ip'ositions. The sweepers being now connected .to the shaft move on out of engagement with the stationary contacts 4 to 4 inclusive and the apparatus is in readiness for a similar connection, it of course being understood that upon the signal for disconnection the plug 53 is removed from the jack 8t). lf instead of station A, station A had called up, the sweepers 7 to 10 inclusive would have been arrested in contact with the stationary contacts 5 toljz inclusive and cir-. cuits similar to those which have been traced through cord circuits C and station A could have been tracedthrough the same cord circuits and the circuits of the station A. Also if the selective device D had not been idle or had not been the first to engage with to the stationA, but, on the other hand, if the selective device D had been idle and was the first of the selective devices to have its sweepers come in contact with a set of stationary contactscorresponding to the station A, precisely similar circuits would have been traced from the station A, selective device D and its connected cord circuits as have already beehtraced through that station, the selective device 3) and its cohera-cs1 nected cord circuits 0. It will now be seen V that in the system illustrated and described there are a plurality of subscribers stations, a plurality of cord circuits and selective devices one corresponding to each cord circuit whereby any of said'stati'ons may be connccted with a given cord circuit. thus be seen that afiexible system is produced by .Which it becomes necessa to supply only a sufiicient number of cor circuits to care for the maximum number of simultaneous calls which is much less than the number of subscribers stations, this be:

mg rendered possible by the fact that every cord circuit is available for connecting any It will station and moreover the selective device or connecting means are made to correspond in number to the cord circuits, thereby greatly cutting down the apparatus over what'it would be where a connecting device is supplied for each subscribers station.

,VJhile in the fore oing the invention has been described as re ating to the connection of subscribers stations to, the cord circuits, it willbe understood that it might be emwith any other apparatus or for connecting sets of conductors generally, and it will also be understood that any two points between which signaling communication is desired,

ployed for connecting subscribers stations will correspond to the subscribers stations.

The apparatus wherebyjconnections are trunked out from an exchange when the, lines of\the called subscriber" do not run directly to the exchange atwhich the call is made but run to another exchange, may now; be described, rolerring to Fig. 1. Inaddition t0 the jacks 80 which connect with subscribers lines running directly to the exchange there may be also rovided jacks 82, 82,vetc., for connecting t e cord circuit at the central station with one of the pairs of trunk conductor's F and F, etc, the connection being efi'ected through selective devices G, G, etc. pairs of selective conductors H, H, etc, one pair of selective conductors corresponding to each trunk line. The selective devices G, G, etc., are identical in construction with the selective devices I), D, etc., reviously described. In the previous escription the contacts 35 mounted upon the frame of the selective devices have not been employed but in the trunking connections these contacts will be brou ht into use. A battery I, common to all t re selective devices G, G, ,etc., is provided for a urpose as will be hereinafter set forth. The electromagnet 25 performs the same function as the magnet 25 and in the same manner as heretofore described. A relay-83 is provided at each of the selective devices for a'purpose as will be hereinafter set forth and also a relay'72 corresponding to each trunk circuit similar function to relay 72 hereinbefore described. In the portion of apparatus under present rea discussion each trunk circuit and its corre- I battery I, contacts relay 85. a sweeper oi spending selective conductors are connected I the selective device G and stationary con to a set of stationary contacts in each of the 1 selective devices G, G, etc., thus the trunk conductors F and their corresponding selective conductors H are connected to the sets oi contacts 4 4?, 4 and 4 and 4 4%, 4, i etc., of the selective devices G, G, etc., While the trunk conductors F and corresponding selective conductors H are connected to the stationary contacts 5*, 5 5 5 and 5", 5, 5, 5 etc., of the selective devices G, G, etc. The sweep- .ers and manner of maintaining connection with them in the selective devices G, G, etc., are the same as those described in connection with the selective devices D, D, etc. The manner of operation of the selective devices G, G, etc., in selecting a trunk is the same as that of selective devices D, D, etc.,.

in selecting a cord circuit, the sweepers being continuously driven and when a set of sweepers engages an idle trunk it 18 arrested to maintain the contact while each of the sets of nected with a subscriber not directly conlhe opnected with the exchan e called. erator then inserts the p ug 53 in one of the trunk jacks 82, 82, etc. Let it be assumed that the jack chosen is 82. Upon the engagement oi' the set of sweepers corresponding to the jack 82 with the cdhtacts of an idle trunk the sweepers will be arrested and cirsuit between the cord circuit C and the trunk conductors F- will be secured. Let itibeiassurncd that the sweepers at the selective device G come in contact with an idle trunk circuit and that the first idle trunk circuit engaged is .11. Upon the contact of the sweepers as referred to, circuit maybe traced from the ground at 61 through tile battery 54, resistance 62, resistance 57, sleeve of jack 82, magnet'25, normall closed contacts 84, a sweeper of the device (I, stationary contact 5 selective .conductor H and normall closed contacts to'ground at 86. The magnet 25' being thus energized operates to disconnect the spool carrying the swee' ers from the driving shaft and hold it in 'ixed position as before described. Energizing of the magnet 25 also has the effect of closing the contacts 34 and 35 thereb. closings. circuit from the ground at 87 t rough the tart 5 through one oi'the selective conductors ll and relay 72 to ground at The energizing of the relay 72 opens the contacts 85 thereby cutting off the-ground connection through the one of the selective conductors lI through which circuit for arresting sweepers is made and thereby making it impossible for sweepers of other selective device which later engage with thescts of contacts corresponding to the trunk in connection from being arrested upon those contacts. the stationary contact 5 described also energizes the relay 83, thereby opening the contacts 84 and breaking the circuit of the magnet 25 through the stationary contact 5 The circuit of this magnet is, however, completed at this stage by the contacts 34.

It will now be seen that the connection of the signaling conductors 51 and 52 of the cord C is now established through the plug 53, trunk jack 82 and stationary contacts 5 and 5 with the trunk signaling conductors F. Connection having been thus established, by repetition of trunking it necessary, with the exchange to which the desired subscriber is directly connected, the cord circuit at the exchange lashncntioncd is plugged into a subscribers jac' corresponding to the jack 80 when the operations of signaling and disconnection, so far as the subscribers stations and cord circuits are concerned, are performed as hercinbcfore described. Upon the signal for disconnection and the withdrawal of the plug 53 from the jack 82 the circuit oi magnet 25 will be broken at the jack and the dciinergizing of this magnet will result in the opening of the contacts 34 and 35, this deenergizing the relays S3 and 72 when the various arts will be returned to the position occupiec before connection, in readiness "for a repetition of the connection.

In Fig. 2 is shown the manner in which a subscribers station is connected with the selector switches of a Strowger automatic s stcm and the apparatus is analogous with slight modifications to that described with reference to the connection of subscribers with cord circuits, as shown in Fig. 1. In Fig. 2 the subscribers stations A" and A etc., are supplied with signaling conductors B", 13', etc., selective conductors E, 15, etc., magnets as 73", for preventing the duplication of connections from the subscribers line to the automatic switches, and selective devices H and 11, etc. Thus far the apparatus is )recisely analogous and operates in exactly t ie same way as .do the corresponding devices for connectin the sub scribers station with the centra station apparatus in Fig. 1. An,automatic Straw ger selective switch is indicated at sufficient to illustrate the ,applicationtof thc-in The making of the circuit through vention but the construction of the switch is peering on page 102 01' volume 8, issue August, 1994. A relay 91, normally closed contacts 92 and a source of current 93 are provided and their functions will bepointed out hereinafter in connection with a description of the operation of the apparatus. Apparatus 9a of well known design is providcd at each of the centralsubscribers stations for controlling the Strowger switches.

The operation of connecting one subscriber to a selective switch is ty ical of similar connections of other subscribers and therefore the operation will be described in connection with one suhscribers station only and for urposes of illustration the rtation A has been chosen.

A subscriber desiring connection removes the receiver vfrom the hook 39 in the usual manner which thereupon closes the circuit through the telephone instruments at the station. The contacts 95 are then closed for a short time, a second or little longer, where by, when the sweepers of one of the selective devices HT, 11", etc., each corresponding to a Strowger switch, as 90, come in contact with a set of stationary contacts corresponding to the calling station A", circuit may be traced from the ground at 95 through the contacts 95, contacts 68, once? the sweepers, relay 91 and battery 93 to the ground at 97. The relay 91 being energized contacts 192 will be closed thereby completing a circuit through the battery 93 and-the magnet 21 whereupon the magnet will be energized and the sweepers of the selective device H will be arrested and the contacts 34 will be closed as described in connection with Fig. 1. The closing of the contacts 34 operates to close a circuit through, and energize, the relay 73 thereby opening the contacts 68 and breaking the circuit through the relay 91 Whereupon the contacts 192 are opened. Contacts 92 are closed at this stage and a shunt established about the contacts 192 thereby maintaining the circuit of the magnet 25 The'signaling conductors 44: and 45 are, upon the arresting of the sweepers of the selective device, connected with the signaling conductors 48 and 17 which are respectively connected to the vertical and rotary relays for operating the Strowger switch. .The application or the relays to the switch wherevby oneoperates to move the switch vertically and the other to rotate it, are well understood as is also the manner of controlling these relays through the signaling conductors, the arrangement and connection being shown and described in the article in Telephbefore referred to. It is unnecesdevice as before described, the circuit will be completed from the ground 96 through con tacts 95 and signaling conductors 4d and 48 to the vertical relay whereby the switch will he stepped up vertically one step. T his will permit the contacts 92 to close with results as previously indicated. The stationary or bank contacts or" the Strowger switch are elevated one step higher than usual with relation to the wiper or spindle contacts, so, that upon the first vertical impulse, the wipers are not brougl'it opposite the rows of bank con-- tacts, but this condition is brought-about by a second vertical impulse. The first vertical impulse then, which is brought about by the closing of the contacts 95, simply raises the switch spindle one step, thereby permitting the closure of the contacts 92 as before referred to. The next impulse, instead of being a rotary impulse as in the ordinary operation of a Strowger switch, is a second vertical impulse which is followed by a rotary in1- pulse caused by the grounding of the conductor45 and thereafter the Strowger switch maybe moved into any desired selective position by alternately grounding the conductors 44 and 45 in a well known manner, the selection by the Strowger switch l eing accomplished in the same manner as, connections were made directly to the switch 90 instead of: through the selective device H; When the conversation has been finished the subscriber returns the receiver to its book thereby opening the transmitter circuit and releasing the selector switch in a well known manner. As the switch returnsto its normal vertical position it comes against one of the contacts 92 and opens the circuit at that point thereby opening the circuit of and deenergizing the magnet 25 whereupon the retaining means of the selective device H is released and the apparatus returns to normal position in readiness for operation to effect other connections as described in connection with the apparatus offig. 1.

y In view of the fact that by the system and apparatus just outlined any subscribcrs eta-- tion may be connected with any Stronger switch, it will be obvious that the number of selective switches need only correspond to those required to serve the maximum number of simultaneous calls which is much less than the nuinber of switches which are re quircd when a Strowger switch for each subscribc'r's station is supplied as. heretofore. As in the case of the'cord circuits of Fig. 1, there is one selectivedcvicc corresponding to the smaller number of connected apparatus, namely, in this case the Strowger switches and thus the system serves to sup- "ply a givennumber'of subscirbers with a m'inimumiamount of apparatus and expense.

The invention'has been described in what is considered its best applications but it may be embodied in various structures without departing from the spirit of the invention. The invention should not, therefore, be limited to the systems or apparatus shown.

what I claim is f 1. In a signaling system, the combination with a subscribers station, of a cord circuit, a common battery connected to said cord circuit, a set of movable cont-actsifixed with relation to each other andgineans for controlling said movable contacts, said set of movable contacts comprising contacts for con,- necting the subscriber's station with. said cord circuit and a contact adaptedmo'close a circuit for the said means for controlling the set of contacts through said common battery simultaneously with the connection of the subscribei"s station with the cord circuit and means actuated by current in the signaling circuit for closing a local circuit through said common battery and means for controlling the movable. contacts but not passing through any of the contacts of said set.

2. In a signaling system, the combination with a su bs cribens station, of signaling conductors and'a set of movable contacts fixed with relation to each other, a signal whereby a subscriber indicates a desire for communication, and means for controlling said movable contacts, said set of movable contacts conmrising contactsfor connecting said sig naling conductors with said subscribers station and a contact adapted to close a circuit through said'means For controlling the said set of contacts and through said signal simultaneously with the connection of the subscribcrs station with the signaling conductor and means actuated by current in the signalmg circuit for closing a local (ll c t thrrurgh said signal and means for controlling said movable contacts but not passing through any of the contacts of said set.

3. n a.signa lin,g system, the combination with a subscribers station, of signaling con ductors, a signal for indicating the desire of the subscriber for "connection, a set of mmable contacts fixed with relation to cachother, a common battery adapted to supply signaling current to connected stations,

and means for controlling said movable contacts, said set of movable contacts comprising contacts for connecting said signal con ductors with saidsubscribers station and a contact adapted to close circuits through said common battery, said signal and said means for controlling said movable contacts a subscriber indicates a desire for communi cation, and means for controlling said movable contacts, said set of movable contacts comprising contacts for connecting said sig naling conductors with said subscribers station and a contact adapted to close a circuit through said means, for controlling the said set of contacts, 'and through said signal simultaneously with the connection of the subscribers station with the signaling conductors and contacts at the subscribers station for controlling the circuit through the means for controlling the said set of movable contacts.

5. In asignaling, system, the combination with a subscriber's station, of signaling conductors and a set of movable contacts fixed with relation to each other, a si nal whereby a subscriber indicates a desire or communication, and means for controlling said movable contacts, said set of movable contacts comprising contacts for connecting said signaling conductors with said subscribers station and a contact adapted to close a circuit through said means for controlling the said set of contacts and through said signal simultaneously with the connection of the subscribers station with the signaling conductors, the said signal and the said means for controlling the said set of contacts being connected in parallel and contacts at the subscribers station for controllin the circuit through the means for controlling the said set of movable contacts.

6. In .a signaling system, the combination with a subscribcrs station provided with the usual receiver hook, of signaling conductors, a set of movable contacts fixed with relation to each other and means for controlling said movable contacts, said set of movable contacts comprising contacts for connecting said signaling conductors with said subscriber's station and a contact ada ted to close a cirouit for the said means or controlling the said set of contacts simultaneously with the connection of the subscriber's station with the signaling conductors and contacts at the subscribers station actuated by the receiver hook for controlling the said means for controlling the said set of movable contacts.

7. In a signaling system, the combination with a subscribers station having a receiver hook, of a cord circuit, a common battery connected to said cord circuit, a set of movable contacts fixed With relation to' each other and means for controlling said movable contacts, said set of movable contacts comprising contacts for connecting the sub-- scribers station with said cord circuit and a 1 contact adapted to close a circuit for the said means for controlling the set of contacts through said. common battery simultaneously with the connection of the subscribers station with the cord circuit and contacts at the subscribers station actuated by the receiver hook for controlling the said mean for controlling the said set of movable contacts.

8. In a signaling system, the combination .With a subscribers station havin a receiver hook, of signaling conductors and a set of movable contacts fixed With relation to each other, a signal whereby a subscriber indicates a desire for communication, and means for controlling said movable contacts, said set of movable contacts comprising contacts for connecting said signaling conductors with said subscribers station and a contact adapted to close acircuit through said means for controlling the said set of contacts and through said signal simultaneously With the connection of the subscribers station with the signaling conductors and contacts at the subscribers station actuated by the receiver hook for controlling the said means for controlling the said set of movable contacts.

9. In a signaling system the combination with a subscribers station having areceiver hook, of signaling conductors and a set of movable contacts fixed with relation to each other, a signal whereby a subscriber indicates a desire for communication, and means for controlling said movable contacts, said i set of movable contacts comprising contacts for connecting said signalin conductors With said subscribers station ano a contact ada 3ted to close a circuit through said means i controlling the said set of *ltftCtS and through said signal simultaneoii iy with the l connection of the subscribers station with i the signaling conductors and contacts at the l subscribers station actuated by the receiver hoolr for controlling the said means for controlling the said set of movable contacts. l 10. In a signalin system,,the combination with a plurality to? subscribers stations, of signaling conductors extending from each of said station's, selective conductors corresponding to each subscribers station, other sets of signaling conductors, selective devices for connecting the conductors extendin from the subscribers stations with the sai other sets of signaling conductors, the signaling and selective conductors corresponding to each station being connected With each of the said selective devic a circuit for each of the selective devices adapted to control its movement, the circuits for controlling the movement of the selective d vices being ada ted to be initially closed through one of i saio selective condnctors and means for l breaking the circuit through the last mentioned conductor upon the establishment of the signaling circuit through a selective device. In testimony whereof I have hereunto set my hand in presence of two subscribing Witnesses.

v\Yitnesses:

R. L. HOGAN, Human HAPIN.

l l l "l 

